State whether the following statements are true or false :
(a) Like charges attract each other.
(b) A charged glass rod attracts a charged plastic straw.
(c) Lightning conductor cannot protect a building from lightning.
(d) Earthquakes can be predicted in advance.
(e) An earthquake of magnitude 2 on Richter Scale is ten times as strong as an earthquake of magnitude 1 on the same Scale.
(f) The plates of earth's crust are continuously moving.
(g) An earthquake is measured and recorded by using an instrument called electrocardiograph.
(a) This statement is False.
Like charges repel each other and unlike charges attract each other.
(b) This statement is True.
A charged glass rod has positive charge on its surface and a charged plastic straw has negative charge on its surface. The charges are opposite in nature and hence, they attract each other.
(c) This statement is False.
Lightening conductor is a device which is used to protect a tall building from lightening. A metallic rod, taller than the building, is installed in the walls of the building during its construction.
(d) This statement is False.
An earthquake is a sudden shaking or trembling of the earth. It is caused by a disturbance deep inside the earth’s crust. It is not possible to predict the occurrence of an earthquake.
(e) This statement is True.
The Richter scale is used to measure the magnitude (or intensity) of an earthquake. It measures the power of an earthquake. The destructive earthquakes have magnitudes higher than 7 on the Richter scale.
(f) This statement is True.
The outermost layer of the earth is fragmented. Each fragment is called a plate. These plates are in continual motion. When they brush past one another, or a plate goes under another due to collision they cause disturbance in the earth’s crust that shows up as an earthquake on the surface of the earth.
(g) This statement is False.
Seismograph is the instrument which is used to measure and record an earthquake. The tremors produce waves on the surface of the earth. These are called seismic waves. These waves are recorded by the seismograph.